Allocate an order-0 folio instead of a page and pass it all the way down
the call chain.  Removes dozens of calls to compound_head().

Link: https://lkml.kernel.org/r/20230116191813.2145215-5-willy@infradead.orgSigned-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Use new_folio instead of new_page throughout, because we allocated it
and know it's an order-0 folio.  Most old_page uses become old_folio,
but use vmf->page where we need the precise page.

Link: https://lkml.kernel.org/r/20230116191813.2145215-4-willy@infradead.orgSigned-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Removes six calls to compound_head(); some inline and some external.

Link: https://lkml.kernel.org/r/20230116191813.2145215-3-willy@infradead.orgSigned-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Replace alloc_zeroed_user_highpage_movable().  The main difference is
returning a folio containing a single page instead of returning the page,
but take the opportunity to rename the function to match other allocation
functions a little better and rewrite the documentation to place more
emphasis on the zeroing rather than the highmem aspect.

Link: https://lkml.kernel.org/r/20230116191813.2145215-2-willy@infradead.orgSigned-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

All callers to find_get_pages_range_tag(), find_get_pages_tag(),
pagevec_lookup_range_tag(), and pagevec_lookup_tag() have been removed.

Link: https://lkml.kernel.org/r/20230104211448.4804-24-vishal.moola@gmail.comSigned-off-by: Vishal Moola (Oracle) <vishal.moola@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Convert function to use folios throughout.  This is in preparation for the
removal of find_get_pages_range_tag().  This change removes 2 calls to
compound_head().

Link: https://lkml.kernel.org/r/20230104211448.4804-23-vishal.moola@gmail.comSigned-off-by: Vishal Moola (Oracle) <vishal.moola@gmail.com>
Acked-by: Ryusuke Konishi <konishi.ryusuke@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Convert function to use folios throughout.  This is in preparation for the
removal of find_get_pages_range_tag().  This change removes 8 calls to
compound_head().

Link: https://lkml.kernel.org/r/20230104211448.4804-22-vishal.moola@gmail.comSigned-off-by: Vishal Moola (Oracle) <vishal.moola@gmail.com>
Acked-by: Ryusuke Konishi <konishi.ryusuke@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Convert function to use folios throughout.  This is in preparation for the
removal of find_get_pages_range_tag().  This change removes 1 call to
compound_head().

Link: https://lkml.kernel.org/r/20230104211448.4804-21-vishal.moola@gmail.comSigned-off-by: Vishal Moola (Oracle) <vishal.moola@gmail.com>
Acked-by: Ryusuke Konishi <konishi.ryusuke@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Convert function to use folios throughout.  This is in preparation for the
removal of find_get_pages_range_tag().  This change removes 1 call to
compound_head().

Link: https://lkml.kernel.org/r/20230104211448.4804-20-vishal.moola@gmail.comSigned-off-by: Vishal Moola (Oracle) <vishal.moola@gmail.com>
Acked-by: Ryusuke Konishi <konishi.ryusuke@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Convert function to use folios throughout. This is in preparation for
the removal of find_get_pages_range_tag(). This change removes 4 calls
to compound_head().

Link: https://lkml.kernel.org/r/20230104211448.4804-19-vishal.moola@gmail.comSigned-off-by: Vishal Moola (Oracle) <vishal.moola@gmail.com>
Acked-by: Ryusuke Konishi <konishi.ryusuke@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Convert function to use folios throughout.  This is in preparation for the
removal of find_get_pgaes_range_tag().  This change removes 8 calls to
compound_head().

Also had to modify and rename gfs2_write_jdata_pagevec() to take in and
utilize folio_batch rather than pagevec and use folios rather than pages. 
gfs2_write_jdata_batch() now supports large folios.

Link: https://lkml.kernel.org/r/20230104211448.4804-18-vishal.moola@gmail.comSigned-off-by: Vishal Moola (Oracle) <vishal.moola@gmail.com>
Reviewed-by: Andreas Gruenbacher <agruenba@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Convert function to use folios throughout.  This is in preparation for the
removal of find_get_pages_range_tag().  This change removes 5 calls to
compound_head().

Initially the function was checking if the previous page index is truly
the previous page i.e.  1 index behind the current page.  To convert to
folios and maintain this check we need to make the check folio->index !=
prev + folio_nr_pages(previous folio) since we don't know how many pages
are in a folio.

At index i == 0 the check is guaranteed to succeed, so to workaround
indexing bounds we can simply ignore the check for that specific index. 
This makes the initial assignment of prev trivial, so I removed that as
well.

Also modify a comment in commit_checkpoint for consistency.

Link: https://lkml.kernel.org/r/20230104211448.4804-17-vishal.moola@gmail.comSigned-off-by: Vishal Moola (Oracle) <vishal.moola@gmail.com>
Acked-by: Chao Yu <chao@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Convert to use a folio_batch instead of pagevec.  This is in preparation
for the removal of find_get_pages_range_tag().

Link: https://lkml.kernel.org/r/20230104211448.4804-16-vishal.moola@gmail.comSigned-off-by: Vishal Moola (Oracle) <vishal.moola@gmail.com>
Acked-by: Chao Yu <chao@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Convert the function to use a folio_batch instead of pagevec.  This is in
preparation for the removal of find_get_pages_range_tag().

Also modified f2fs_all_cluster_page_ready to take in a folio_batch instead
of pagevec.  This does NOT support large folios.  The function currently
only utilizes folios of size 1 so this shouldn't cause any issues right
now.

This version of the patch limits the number of pages fetched to
F2FS_ONSTACK_PAGES.  If that ever happens, update the start index here
since filemap_get_folios_tag() updates the index to be after the last
found folio, not necessarily the last used page.

Link: https://lkml.kernel.org/r/20230104211448.4804-15-vishal.moola@gmail.comSigned-off-by: Vishal Moola (Oracle) <vishal.moola@gmail.com>
Acked-by: Chao Yu <chao@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Convert function to use a folio_batch instead of pagevec.  This is in
preparation for the removal of find_get_pages_range_tag().

Link: https://lkml.kernel.org/r/20230104211448.4804-14-vishal.moola@gmail.comSigned-off-by: Vishal Moola (Oracle) <vishal.moola@gmail.com>
Acked-by: Chao Yu <chao@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Convert function to use a folio_batch instead of pagevec. This is in
preparation for the removal of find_get_pages_tag().

Link: https://lkml.kernel.org/r/20230104211448.4804-13-vishal.moola@gmail.comSigned-off-by: Vishal Moola (Oracle) <vishal.moola@gmail.com>
Acked-by: Chao Yu <chao@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Convert function to use a folio_batch instead of pagevec.  This is in
preparation for the removal of find_get_pages_range_tag().

Link: https://lkml.kernel.org/r/20230104211448.4804-12-vishal.moola@gmail.comSigned-off-by: Vishal Moola (Oracle) <vishal.moola@gmail.com>
Acked-by: Chao Yu <chao@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Convert the function to use folios throughout.  This is in preparation for
the removal of find_get_pages_range_tag().  Now supports large folios. 
This change removes 11 calls to compound_head().

Link: https://lkml.kernel.org/r/20230104211448.4804-11-vishal.moola@gmail.comSigned-off-by: Vishal Moola (Oracle) <vishal.moola@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

This is in preparation for the removal of find_get_pages_range_tag().  Now
also supports the use of large folios.

Since tofind might be larger than the max number of folios in a
folio_batch (15), we loop through filling in wdata->pages pulling more
batches until we either reach tofind pages or run out of folios.

This function may not return all pages in the last found folio before
tofind pages are reached.

Link: https://lkml.kernel.org/r/20230104211448.4804-10-vishal.moola@gmail.comSigned-off-by: Vishal Moola (Oracle) <vishal.moola@gmail.com>
Acked-by: Paulo Alcantara (SUSE) <pc@cjr.nz>
Cc: Tom Talpey <tom@talpey.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Convert function to use a folio_batch instead of pagevec.  This is in
preparation for the removal of find_get_pages_range_tag().

Also some minor renaming for consistency.

Link: https://lkml.kernel.org/r/20230104211448.4804-9-vishal.moola@gmail.comSigned-off-by: Vishal Moola (Oracle) <vishal.moola@gmail.com>
Acked-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Convert function to use folios throughout.  This is in preparation for the
removal of find_get_pages_range_tag().  Now also supports large folios.

Link: https://lkml.kernel.org/r/20230104211448.4804-8-vishal.moola@gmail.comSigned-off-by: Vishal Moola (Oracle) <vishal.moola@gmail.com>
Acked-by: David Sterba <dsterba@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Convert function to use folios throughout.  This is in preparation for the
removal of find_get_pages_range_tag().

Link: https://lkml.kernel.org/r/20230104211448.4804-7-vishal.moola@gmail.comSigned-off-by: Vishal Moola (Oracle) <vishal.moola@gmail.com>
Acked-by: David Sterba <dsterba@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Convert to use folios throughout.  This function is in preparation to
remove find_get_pages_range_tag().

Also modify this function to write the whole batch one at a time, rather
than calling for a new set every single write.

Link: https://lkml.kernel.org/r/20230104211448.4804-6-vishal.moola@gmail.comSigned-off-by: Vishal Moola (Oracle) <vishal.moola@gmail.com>
Tested-by: David Howells <dhowells@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Convert function to use folios throughout.  This is in preparation for the
removal of find_get_pages_range_tag().  This change removes 8 calls to
compound_head(), and the function now supports large folios.

Link: https://lkml.kernel.org/r/20230104211448.4804-5-vishal.moola@gmail.comSigned-off-by: Vishal Moola (Oracle) <vishal.moola@gmail.com>
Reviewed-by: Matthew Wilcow (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Convert function to use folios.  This is in preparation for the removal of
find_get_pages_range_tag().  This change removes 2 calls to
compound_head().

Link: https://lkml.kernel.org/r/20230104211448.4804-4-vishal.moola@gmail.comSigned-off-by: Vishal Moola (Oracle) <vishal.moola@gmail.com>
Reviewed-by: Matthew Wilcow (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

This is the equivalent of find_get_pages_range_tag(), except for folios
instead of pages.

One noteable difference is filemap_get_folios_tag() does not take in a
maximum pages argument.  It instead tries to fill a folio batch and stops
either once full (15 folios) or reaching the end of the search range.

The new function supports large folios, the initial function did not since
all callers don't use large folios.

Link: https://lkml.kernel.org/r/20230104211448.4804-3-vishal.moola@gmail.comSigned-off-by: Vishal Moola (Oracle) <vishal.moola@gmail.com>
Reviewed-by: Matthew Wilcow (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Patch series "Convert to filemap_get_folios_tag()", v5.

This patch series replaces find_get_pages_range_tag() with
filemap_get_folios_tag().  This also allows the removal of multiple calls
to compound_head() throughout.

It also makes a good chunk of the straightforward conversions to folios,
and takes the opportunity to introduce a function that grabs a folio from
the pagecache.


This patch (of 23):

Add function filemap_grab_folio() to grab a folio from the page cache. 
This function is meant to serve as a folio replacement for
grab_cache_page, and is used to facilitate the removal of
find_get_pages_range_tag().

Link: https://lkml.kernel.org/r/20230104211448.4804-1-vishal.moola@gmail.com
Link: https://lkml.kernel.org/r/20230104211448.4804-2-vishal.moola@gmail.comSigned-off-by: Vishal Moola (Oracle) <vishal.moola@gmail.com>
Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Pass vm_flags as a parameter to shmem_is_huge, rather than reading the
flags from the vm_area_struct in question.  This allows the updated flags
from hugepage_madvise to be passed to the check, which is necessary
because madvise does not update the vm_area_struct's flags until after
hugepage_madvise returns.

This fixes an issue when shmem_enabled=madvise, where MADV_HUGEPAGE on
shmem was not able to register the mm_struct with khugepaged.  Prior to
cd89fb06, the mm_struct was registered by MADV_HUGEPAGE regardless of
the value of shmem_enabled (which was only checked when scanning vmas).

Link: https://lkml.kernel.org/r/20230113023011.1784015-1-stevensd@google.com
Fixes: cd89fb06 ("mm,thp,shmem: make khugepaged obey tmpfs mount flags")
Signed-off-by: David Stevens <stevensd@chromium.org>
Cc: David Stevens <stevensd@chromium.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Rik van Riel <riel@surriel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

__GFP_ATOMIC serves little purpose.  Its main effect is to set
ALLOC_HARDER which adds a few little boosts to increase the chance of an
allocation succeeding, one of which is to lower the water-mark at which it
will succeed.

It is *always* paired with __GFP_HIGH which sets ALLOC_HIGH which also
adjusts this watermark.  It is probable that other users of __GFP_HIGH
should benefit from the other little bonuses that __GFP_ATOMIC gets.

__GFP_ATOMIC also gives a warning if used with __GFP_DIRECT_RECLAIM.
There is little point to this.  We already get a might_sleep() warning if
__GFP_DIRECT_RECLAIM is set.

__GFP_ATOMIC allows the "watermark_boost" to be side-stepped.  It is
probable that testing ALLOC_HARDER is a better fit here.

__GFP_ATOMIC is used by tegra-smmu.c to check if the allocation might
sleep.  This should test __GFP_DIRECT_RECLAIM instead.

This patch:
 - removes __GFP_ATOMIC
 - allows __GFP_HIGH allocations to ignore watermark boosting as well
   as GFP_ATOMIC requests.
 - makes other adjustments as suggested by the above.

The net result is not change to GFP_ATOMIC allocations.  Other
allocations that use __GFP_HIGH will benefit from a few different extra
privileges.  This affects:
  xen, dm, md, ntfs3
  the vermillion frame buffer
  hibernation
  ksm
  swap
all of which likely produce more benefit than cost if these selected
allocation are more likely to succeed quickly.

[mgorman: Minor adjustments to rework on top of a series]
Link: https://lkml.kernel.org/r/163712397076.13692.4727608274002939094@noble.neil.brown.name
Link: https://lkml.kernel.org/r/20230113111217.14134-7-mgorman@techsingularity.netSigned-off-by: NeilBrown <neilb@suse.de>
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Thierry Reding <thierry.reding@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

GFP_ATOMIC allocations get flagged ALLOC_HARDER which is a vague
description.  In preparation for the removal of GFP_ATOMIC redefine
__GFP_ATOMIC to simply mean non-blocking and renaming ALLOC_HARDER to
ALLOC_NON_BLOCK accordingly.  __GFP_HIGH is required for access to
reserves but non-blocking is granted more access.  For example, GFP_NOWAIT
is non-blocking but has no special access to reserves.  A __GFP_NOFAIL
blocking allocation is granted access similar to __GFP_HIGH if the only
alternative is an OOM kill.

Link: https://lkml.kernel.org/r/20230113111217.14134-6-mgorman@techsingularity.netSigned-off-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: NeilBrown <neilb@suse.de>
Cc: Thierry Reding <thierry.reding@gmail.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

As there are more ALLOC_ flags that affect reserves, define what flags
affect reserves and clarify the effect of each flag.

Link: https://lkml.kernel.org/r/20230113111217.14134-5-mgorman@techsingularity.netSigned-off-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: NeilBrown <neilb@suse.de>
Cc: Thierry Reding <thierry.reding@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

A high-order ALLOC_HARDER allocation is assumed to be atomic.  While that
is accurate, it changes later in the series.  In preparation, explicitly
record high-order atomic allocations in gfp_to_alloc_flags().

Link: https://lkml.kernel.org/r/20230113111217.14134-4-mgorman@techsingularity.netSigned-off-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: NeilBrown <neilb@suse.de>
Cc: Thierry Reding <thierry.reding@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

RT tasks are allowed to dip below the min reserve but ALLOC_HARDER is
typically combined with ALLOC_MIN_RESERVE so RT tasks are a little
unusual.  While there is some justification for allowing RT tasks access
to memory reserves, there is a strong chance that a RT task that is also
under memory pressure is at risk of missing deadlines anyway.  Relax how
much reserves an RT task can access by treating it the same as __GFP_HIGH
allocations.

Note that in a future kernel release that the RT special casing will be
removed.  Hard realtime tasks should be locking down resources in advance
and ensuring enough memory is available.  Even a soft-realtime task like
audio or video live decoding which cannot jitter should be allocating both
memory and any disk space required up-front before the recording starts
instead of relying on reserves.  At best, reserve access will only delay
the problem by a very short interval.

Link: https://lkml.kernel.org/r/20230113111217.14134-3-mgorman@techsingularity.netSigned-off-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: NeilBrown <neilb@suse.de>
Cc: Thierry Reding <thierry.reding@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Patch series "Discard __GFP_ATOMIC", v3.

Neil's patch has been residing in mm-unstable as commit 2fafb4fe8f7a ("mm:
discard __GFP_ATOMIC") for a long time and recently brought up again. 
Most recently, I was worried that __GFP_HIGH allocations could use
high-order atomic reserves which is unintentional but there was no
response so lets revisit -- this series reworks how min reserves are used,
protects highorder reserves and then finishes with Neil's patch with very
minor modifications so it fits on top.

There was a review discussion on renaming __GFP_DIRECT_RECLAIM to
__GFP_ALLOW_BLOCKING but I didn't think it was that big an issue and is
orthogonal to the removal of __GFP_ATOMIC.

There were some concerns about how the gfp flags affect the min reserves
but it never reached a solid conclusion so I made my own attempt.

The series tries to iron out some of the details on how reserves are used.
ALLOC_HIGH becomes ALLOC_MIN_RESERVE and ALLOC_HARDER becomes
ALLOC_NON_BLOCK and documents how the reserves are affected.  For example,
ALLOC_NON_BLOCK (no direct reclaim) on its own allows 25% of the min
reserve.  ALLOC_MIN_RESERVE (__GFP_HIGH) allows 50% and both combined
allows deeper access again.  ALLOC_OOM allows access to 75%.

High-order atomic allocations are explicitly handled with the caveat that
no __GFP_ATOMIC flag means that any high-order allocation that specifies
GFP_HIGH and cannot enter direct reclaim will be treated as if it was
GFP_ATOMIC.


This patch (of 6):

__GFP_HIGH aliases to ALLOC_HIGH but the name does not really hint what it
means.  As ALLOC_HIGH is internal to the allocator, rename it to
ALLOC_MIN_RESERVE to document that the min reserves can be depleted.

Link: https://lkml.kernel.org/r/20230113111217.14134-1-mgorman@techsingularity.net
Link: https://lkml.kernel.org/r/20230113111217.14134-2-mgorman@techsingularity.netSigned-off-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: NeilBrown <neilb@suse.de>
Cc: Thierry Reding <thierry.reding@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

There is 8 byte page_ext->flags field allocated per page whenever
CONFIG_PAGE_EXTENSION is enabled.  However, not every user of page_ext
uses flags.  Therefore, check whether flags is needed at least by one user
and if so allocate space for it.

For example when page_table_check is enabled, on a machine with 128G
of memory before the fix:

[    2.244288] allocated 536870912 bytes of page_ext
after the fix:
[    2.160154] allocated 268435456 bytes of page_ext

Also, add a kernel-doc comment before page_ext_operations that describes
the fields, and remove check if need() is set, as that is now a required
field.

[pasha.tatashin@soleen.com: address comments from Mike Rapoport]
  Link: https://lkml.kernel.org/r/20230117202103.1412449-1-pasha.tatashin@soleen.com
Link: https://lkml.kernel.org/r/20230113154253.92480-1-pasha.tatashin@soleen.comSigned-off-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Acked-by: David Hildenbrand <david@redhat.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: David Rientjes <rientjes@google.com>
Reviewed-by: Mike Rapoport (IBM) <rppt@kernel.org>
Cc: Charan Teja Kalla <quic_charante@quicinc.com>
Cc: Li Zhe <lizhe.67@bytedance.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

__HAVE_ARCH_PTE_SWP_EXCLUSIVE is now supported by all architectures that
support swp PTEs, so let's drop it.

Link: https://lkml.kernel.org/r/20230113171026.582290-27-david@redhat.comSigned-off-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Let's support __HAVE_ARCH_PTE_SWP_EXCLUSIVE by using bit 1.  This bit
should be safe to use for our usecase.

Most importantly, we can still distinguish swap PTEs from PAGE_NONE PTEs
(see pte_present()) and don't use one of the two reserved attribute masks
(1101 and 1111).  Attribute mask 1100 and 1110 now identify swap PTEs.

While at it, remove SWP_TYPE_BITS (not really helpful as it's not used in
the actual swap macros) and mask the type in __swp_entry().

Link: https://lkml.kernel.org/r/20230113171026.582290-26-david@redhat.comSigned-off-by: David Hildenbrand <david@redhat.com>
Cc: Chris Zankel <chris@zankel.net>
Cc: Max Filippov <jcmvbkbc@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Let's support __HAVE_ARCH_PTE_SWP_EXCLUSIVE just like we already do on
x86-64.  After deciphering the PTE layout it becomes clear that there are
still unused bits for 2-level and 3-level page tables that we should be
able to use.  Reusing a bit avoids stealing one bit from the swap offset.

While at it, mask the type in __swp_entry(); use some helper definitions
to make the macros easier to grasp.

Link: https://lkml.kernel.org/r/20230113171026.582290-25-david@redhat.comSigned-off-by: David Hildenbrand <david@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Let's support __HAVE_ARCH_PTE_SWP_EXCLUSIVE by using bit 10, which is yet
unused for swap PTEs.

The pte_mkuptodate() is a bit weird in __pte_to_swp_entry() for a swap PTE
...  but it only messes with bit 1 and 2 and there is a comment in
set_pte(), so leave these bits alone.

While at it, mask the type in __swp_entry().

Link: https://lkml.kernel.org/r/20230113171026.582290-24-david@redhat.comSigned-off-by: David Hildenbrand <david@redhat.com>
Cc: Richard Weinberger <richard@nod.at>
Cc: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Cc: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Let's support __HAVE_ARCH_PTE_SWP_EXCLUSIVE by stealing one bit from the
type.  Generic MM currently only uses 5 bits for the type
(MAX_SWAPFILES_SHIFT), so the stolen bit was effectively unused.

While at it, mask the type in __swp_entry().

Link: https://lkml.kernel.org/r/20230113171026.582290-23-david@redhat.comSigned-off-by: David Hildenbrand <david@redhat.com>
Cc: "David S. Miller" <davem@davemloft.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>